1. Field of Invention
This invention relates to methods and systems for spatial processing in wireless systems.
2. Description of Related Art
As wireless communication systems such as Enhanced Data Rates for Global Evolution (EDGE) are standardized, the importance of providing clear and cost-effective communication techniques increases. Various obstacles include mitigating the effects of noise, co-channel interference (CCI), which results from multiple communication channels using the same frequency spectrum, and Rayleigh fading and inter-symbol interference (ISI), which can result when transmitted signals travel along several paths to an intended receiver.
Currently, noise, Rayleigh fading, ISI and CCI can be mitigated by using some form of equalizer in concert with multiple antennas, each antenna having various electronic front-ends. Unfortunately, electronic front-ends can be expensive and require substantial power. Accordingly, new methods and systems that can accommodate large numbers of antennas without these problems are desirable.
Various techniques are provided for antenna selection and weight calculation for a transmission system having multiple antennas.
The present invention provides systems and methods for selecting a subset of antennas in a receiver having N antennas and L electronic front-ends. The receiver first samples the signals received on each of the N antennas and the channel characteristics for each received signal is calculated. The signal-to-interference-plus-noise (SINR) ratio for various combinations of antennas is estimated and a subset of up to L antennas is selected to provide an advantageous SINR.
The present invention also provides systems and methods for selecting a subset of antennas in a transmitter having N number of antennas and L weighting devices and electronic front-ends. A receiver first samples received signals for each of the N transmitter antennas and the channel characteristics for each received signal are calculated. The signal-to-interference-plus-noise (SINR) ratio for various combinations of antennas is estimated and a subset of up to L antennas are selected to provide an advantageous SINR. Each transmitted signal is also weighted to further provide an advantageous SINR at the receiver.
Other features and advantages of the present invention are described below and are apparent from the accompanying drawings and from the detailed description which follows.